Android中利用LinearLayout動態添加控件

在androidUI佈局中，一般都是利用xml來佈局控件，這是比較方便和直觀的，但是有時卻需要動態生成，下面就舉2個簡單例子來說明怎麼動態添加控件：

 

1.動態添加2個垂直排列的Button

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     @Override  
        public void onCreate(Bundle savedInstanceState) {  
            super.onCreate(savedInstanceState);  
           //setContentView(R.layout.main);        
           final LinearLayout layout2=new LinearLayout(this);  
            layout2.setOrientation(LinearLayout.VERTICAL);  
            Button btn1=new Button(this);  
            setContentView(layout2);  
            Button btn2=new Button(this);  
            btn1.setText("Button1");  
            btn2.setText("Button2");  
            layout2.addView(btn1);  
            layout2.addView(btn2);  
             
              
           setContentView(layout2);  
    }  

final LinearLayout layout2=new LinearLayou(this);

定義一個LinearLayout ，參數爲context在這兒即爲this

layout2.setOrientation(LinearLayout.VERTICAL);

設置layout格式爲vertical，豎直排列

 

2.在Button的click事件中動態添加一個button

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    OnClickListener listen1;  
       @Override  
       public void onCreate(Bundle savedInstanceState) {  
           super.onCreate(savedInstanceState);  
          //setContentView(R.layout.main);        
          final LinearLayout layout2=new LinearLayout(this);  
           layout2.setOrientation(LinearLayout.VERTICAL);  
           Button btn1=new Button(this);  
           setContentView(layout2);  
           Button btn2=new Button(this);  
           btn1.setText("Button1");  
           btn2.setText("Button2");  
           layout2.addView(btn1);  
           layout2.addView(btn2);         
           listen1 = new OnClickListener() {  
            public void onClick(View v) {  
                setTitle("點擊button1 ");  
                Button btn3=new Button(v.getContext());  
                layout2.addView(btn3);  
                btn3.setText("Button3");  
                  
                  
            }  
        };  
         btn1.setOnClickListener(listen1);  
       }  

與上一例子區別就是，在Button的OnClickListener中動態添加控件，需要注意的一點是 Button btn3=new Button(v.getContext);參數v.getContext爲當前view的context，爲什麼例子1中用this作爲context呢，呵呵，這是因爲this即當前的activity，而activity又是context的子類，所以this就可以直接作爲activity了。

查了下，context派生的類有：
java.lang.Object
   ↳ 	android.content.Context
Known Direct Subclasses
ContextWrapper , MockContext

Known Indirect Subclasses
AbstractInputMethodService , Activity , ActivityGroup , AliasActivity , Application , ContextThemeWrapper , ExpandableListActivity , InputMethodService , IntentService , IsolatedContext , LauncherActivity , ListActivity , MockApplication , MutableContextWrapper , PreferenceActivity , RenamingDelegatingContext , Service , TabActivity